It was known in the 1950s that semiconductorp-n junctions responded to alpha particles by producing voltage pulses. However, the common method of determining the energy spectrum of energetic particles at that time relied on the use of very large and cumbersome magnetic spectrometers and ionization chambers. It was at this time in the mid to late 1950s that James Mayer demonstrated the first semiconductor, broad area, spectrometer which measured the energies of the particles rather than just detecting their impact. Mayer's discovery was that the ionization of Si and Ge by charged particles could be used, in a small, compact device, to collect the electrons and holes that were created and thereby measure the energy of the incident particles. The concept of the surface-barrier particle detector that Mayer first developed served as a cornerstone for the rapid development of numerous research areas. Because of its small size and compactness, the surface-barrier particle detector almost immediately started replacing many of the cumbersome detectors in use at that time, i.e. magnetic spectrometers and ionization chambers, revolutionizing low energy nuclear structure physics almost overnight. These semiconductor spectrometers led to the practical development of many modern materials analysis techniques that have wide spread use today, such as X-ray fluorescence and ion beam analysis of materials, including Rutherford backscattering, ion channeling, and X-ray spectrometry based on alpha particle sources.
Particle detectors
Mayer played a pivotal role in the application of particle detectors to the fledgling field of ion beam analysis and the development of this field into a major analytical tool. He went on to define many of the advances in thin film science of the 1970s and 80s, including thin film reactions and kinetics, solid phase regrowth of semiconductors, ion beam mixing for the formation of metastable alloys, implantation disorder and impurity location in semiconductors, and the study of thin dielectric films. In the rapid surge of industrial interest in ion implantation of Si, starting around 1965, Mayer and his coworkers used ion channeling to understand defect production during dopant ion implantation into Si, the recovery of this damage, and the activation of dopants during subsequent anneals, thereby making ion implantation a viable tool for the production of integrated circuits. In 1967, he was chosen by Academic Press to author the first monograph on Ion Implantation of Semiconductors and by 1970 ion implantation first began being used in the commercial production of integrated circuits.
Papers and books
His work resulted in more than 750 papers and 12 books which have garnered in excess of 17,000 citations. He mentored 40 PhD students and numerous postdoctoral scholars during his academic career at Caltech, Cornell and Arizona State University.
